In recent years, replacement of lighting sources from incandescent lamps or fluorescent lamps to energy saving and long life light sources such as Light-emitting diodes (LED) in luminaires is in progress. Also, for example, new lighting sources such as Electro-Luminescence (EL) or Organic light-emitting diode (OLED) are also developed.
On the other hand, as a high-luminance lighting source, there are luminaires using, for example, a halogen lamp. In such luminaires, dimming is achieved by performing phase control of a commercial power supply using a dimmer configured so as to control a phase in which a triac is turned ON. There is a case where a voltage of the commercial power supply is lowered by using a magnetic transformer or an electronic transformer. The dimmer and the electronic transformer require a minimum load current for a stable operation. Therefore, it is preferable that the lighting source such as LED may be illuminated by an AC voltage lowered by the electronic transformer or the like, and may be dimmed by the dimmer.